At the very least it will distract him for a while. And when the relationship ends he'll have a whole new set of issues to keep him occupied. Eventually, your imaginary existential issues will vanish by your mid-20s anyway.
My advice to the original poster is to print out a copy of that big long rant, and keep it in a drawer somewhere. Look at it once a year or so. When you get to the point that you can't read it without wanting to travel back in time and slap yourself for being so whiny and self-important, you'll know you've outgrown those issues.
